1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a spectrometer including a vertical stack structure and a non-invasive biometric sensor including the spectrometer, and more particularly, to a spectrometer that may be easily manufactured while having high resolution and sensitivity due to reduced light loss and a non-invasive biometric sensor including the spectrometer.
2. Description of the Related Art
A method considered to have the most potential as a method for non-invasive blood sugar measurement is a method of spectroscopic analysis of light including a biometric signal, which is scattered by a skin after being radiated to the skin. Recently, with improvements in performance of mobile apparatuses such as mobile phones, various attempts have been made to integrate a non-invasive biometric sensor into a mobile apparatus. To this end, it is necessary to develop a micro spectrometer that may be installed in a mobile apparatus.
For example, a linear variable filter (LVF)-based spectrometer has a structure in which a spacer having a gradually changing thickness is disposed on a plurality of photodiode pixels. Based on the principle that the transmission wavelength varies depending on the thickness of the spacer, lights of different wavelength bands may be sensed in the respective pixels. Also, a filter array-based spectrometer has a structure in which band-pass filters (BPFs) of different transmission bands are disposed in respective photodiode pixels.
The above spectrometers may be manufactured to be a micro sized. However, since a plurality of photodiode pixels are arranged in a horizontal direction, the resolution thereof is difficult to increase. Also, since the spacer or the BPFs absorb lights of wavelength bands other than the transmission bands, sensitivity degradation may occur due to light loss. For example, when N wavelength bands (where N is an integer equal to or greater than 1) are to be analyzed by the spectrometer, N different BPFs are used and the amount of light sensed by each pixel is only 1/N of the amount of light that is actually input to the pixel.